Wood pulp separator



Jan. 23, 1945. p|poN|Us 2,367,961

WOOD PULP SEPARATOR Filed May 14, 1941 2 Sheets-Sheet l lnbentor wan(Ittorneg J 23, 19 5 A. H. PIPONIUS 2,367,961

WOOD PULP SEPARATOR Filed May 14, 1941 2 Sheets-Sheet 2 3nvent or(Tttor'neg ?atented Jan. 23, 1945 UNITED STATES PATENT oFncE WOOD PULPSEPARATOR Adolf Henrik Piponius, Tammerfors, Finland Application May 14,1941, Serial No. 393,471

In Sweden May 15, 1940 v1 Claim.

This invention relates to a separator for the removal of impurities frompulp, as e, g. from sulphite cellulose.

As known, the separators used for this purpose can be divided into threegroups:

p 1. Separators, which by the means of a strainer or of a plate, whichis furnished with perforations, through which the impurities are removedfrom the pulp, because of their various size and form. 1

2. Separators, in which the separation is done by means of thecentrifugal force of a swiftly rotating drum. The separation of theimpurities is based upon the diiierence of their specific gravity.

3. Separators, which are combinations of the two above mentionedseparators, and in which the purification is based upon the diflerencein size and specific gravity.

In separators of group 1 'it is necessary to use a large strainingsurface, if thorough purification is desirable, and this causes a greatloss of fibres with the impurities.

In separators of group 2 the power consumption is great, compared withthe separation effect. Impurities, of which the specific gravity is thesame as that of the pulp, also become mixed with the latter.

In separators of group 3, the advantages of groups 1 and 2 are united,but as a drawback there is a great consumption of power in com- .parisonto the separation effect, this because of the fact that the strainers inknown separators are arranged rotatably with the drum, whereby themovement energy of the pulp leaving the drum is lost. The loss of poweris also increased because a special arrangement, such as a screw or thelike, is required in order to keep the strainer open, which causes asweeping or similar effect. The purpose of the present invention is todiminish the power consumption by using the n 3. Strainer drums I0 and2. The strainer has the same rotation direction as the drum, but adiiferent rotation velocity, bywhich the difference in velocity causesthe sweeping movement. In order that the movement energy may beutilized, the rotation velocity of the strainer must be less than thatof the peripheric velocity of the drum.

3. The strainer has a rotating direction 'contrary to the drum, by whichthe resultant of the peripheric. velocity of both, causes the sweepingmovement.

The simplest solution is, that a cylindrical strainer is placed aroundthe drum.

Case 1 permits a simpler strainer construction.

Cases 2 and 3 are to be considered on special occasions only.

As it sometimes may happen at pulp mills that bigger impurities, as e.g. tree branches, may enter such a contrivance, a pre-strainer is to beplaced in the innermost drum with proper arrangements for the separationof such impurities.

This invention is closer specified in the following and in the drawings,which shows some different forms of construction.

Fig. 1 shows one form of the invention utilizing a single drum and twostrainers and Fig.- 2 shows a modification in which there are tworotatable drums and two strainers,

In the form shown in Fig. 1, the pulp separator consists of a drum I,which is fixed by a cross arm 2 to a vertical shaft 3, which is'rotatably arranged in bearings 4, fixed in a frame 5, which shaft isdriven by a motor 6, through a power transmission, consisting of a,motor pulley 1., a belt 8 and a pulley 9, which is fixed to the shaft Hare arranged to rotate around the drum I.

moving energy of the pulp leaving the drum, in

order to accomplish a sweeping movement on the strainer. v

The sweeping efiect is accomplished thus, in accordance with theinvention, that the drum and the strainer are arranged relating to eachother so, that the velocity of the pulp coming out of the strainer andout of the drum, is different.

This is to be achieved as follows:

1. The strainer is kept in its place and the pulp coming out of the drumhas quite a velocity in the direction toward the strainer, which causesthe above mentioned sweeping movement.

The pulp to be purified, is fed into the machine through-a channel l2.If the pulp is not under high enough pressure to rise in the drum 1, animpeller I3 is fixed to shaft 3 to drive the pulp into the drum. In thedrum there are arranged baflles M, which cause the pulp to rotate at thesame velocity as the drum, and the pulp is thrown over the edge l5against the strainer l0. As the pulp is thrown out of the drum withgreat velocity, a reinforcement ring I 6 is secured to the strainer atthis place.

The centrifugal force pushes the impurities, which are heavier than thepulp, against the drum, to which horizontal bailies H are attached, inorder to prevent impurities from travelling with the pulp. If there areimpurities with the 2 :pulp, which are lighter, they rise to the 811moi. the pulp and are thrown out overthe inclined A part of theimpurities of the same weight .as the pulp and travel with it. Asthepulp is thrown out the drum inrthe direction oithe tangent it rotates,after having struck the strainer.

3 of the motor], by means of the member ll.

Thearrangementissulcluthatthepulpisdis tributed to both drumssimultaneously, which thus work in parallel. The pulp travels upwards inthe drums and is cleaned in the-same way as inthe separator shown inFig. 1 and is finally II, in a screw-like motiondownwards along it.

- The lower part of the strainer is taperedto prevent too rapiddescentoi thepulpi The strainer III is made to retain'as much aspossible oi the usable'pulp fibres, but-to allow as much as possible orthe impurities to pass through it. The quantity which has passedthrough, still contains inside the strainer II, is removed through thechannel' it. The impure pulp, which has remained .between the strainersIll and Ii, is removed through the channel 20 to-be used for secondquality purposes, or to be further purifled. If the .pulp, which hasbeen removed through the channel is, has lost too much water, water canbe added to the pulp at a suitable place in the drum 1 or on thestrainer III.

When the machine is stopped for cleaning, the impurities, whichhaveremained in the drum, drop down through the slot 2| into the drain 22.The cone-shaped casing 23 prevents the impurities from getting into thesupply channel 12. The cleaning of theseparator can be renderedeffective after the machine has been stopped, e. g., by the aid of a jetoiwater or steam.

In the form shown in Fig. 2, the pul to be purified is conductedthrougha channel [2 into two concentric drums 26 and 21 mixed to the shaftthrown against the strainer 10 to continue its course as in Fig. 1.During the cleaning, the impurities are removed throulh the holes 2! toa bowl 3| and from there to the drain 2!.

The drawings and the appended specification are, of course, onlyintended to illustrate the principle of the invention. The actual modesof construction of the separtors can vary very much within the scope ofthe present invention. This refers particularly to the relative positionof the rotatably mounted drums and the strainers, and

their position in relation to the feeding channel,

through which the pulp is led into the separator. The shaft of the drumscan' be in any desired position, even though the drawings showseparators withvertical shaft.

What I claim and desire to secure by Letters Patent is:

'A separator for the removal of impurities from wood pulp comprising avertically arranged rotatably mounted drum, means for feeding the woodpulp to said drum, said drum separating separate impurities from saidwood pulp and driven by the liquid thrown thereagainst from the drum,the peripheral velocity of said drum 'and strainer being different andin the same direction so that the energy of the pulp leaving said drumisutilized for cleansing said strainer.

ADOLF HENRIK PIPONIUS.

